Over the course of her past year battling cancer, the Princess of Wales has come to rely on her mother Carole Middleton perhaps more than at any other time in her life. 

When Kate issued her touching three-minute family video revealing that she had finished her course of preventative chemotherapy in September, Carole featured heavily.

And although the usually very healthy princess had avoided hospital for most of her life until recently, she did have one previous health scare which reportedly made her mother ‘very worried’.

When Kate was boarding at the elite £42,900-a-year private school Marlborough College she discovered a mystery lump on the left-hand side of her head.

After concerned staff from the school called her, Carole took her daughter to see their family doctor who considered the lump ‘potentially serious’, according to royal author Katie Nicholl.

The future princess was operated on within a few days, but the surgery left a three-inch scar on Kate’s head.

A housemistress at the school during Kate’s time there, Ann Patching, told Nicholl: ‘I can remember the incident and her having an operation. 

‘I don’t recall anything happening on the hockey pitch (field) that had anything to do with the lump,’ she said after the media reported that the health scare might have been the result of a sporting accident.

Carole Middleton, pictured with Kate while out shopping in south-west London in 2006, has always enjoyed a close relationship with her daughter

The scar on Kate’s temple was first spotted when she wore her hair tied back at a dinner at Clarence House in 2011

An official statement at the time explained that the scar, which is usually hidden as the princess tends to wear her hair loose in public, was the result of an operation when she was a child

Kate and her sister Pippa playing hockey at Marlborough College in 2000. The operation on her head took place while she was studying at the boarding school in Wiltshire

Kate had become hockey captain while at the school in Wiltshire.

Nicholl writes in her 2013 book, Kate: The Future Queen, that the operation was her ‘only unhappy spell’ at the school as it caused her to stop playing the sport.

Mrs Patching told her: ‘Catherine had the operation during her term time. She was back at school very soon afterwards. 

‘As usual, nothing was too much of a big deal for her. You could never accuse Catherine of being a drama queen, but Carole was very worried, as any mother would be.’

A former pupil told Nicholl that the operation ‘was pretty serious’ and alarmed everyone, as it had happened shortly after another pupil, Hugo McDermott, had died from a brain tumour. 

But following the operation, Kate’s scar began to fade and usually it is hidden as she tends to wear her hair loose.

The blemish was first spotted in 2011 when the princess was carrying out her first solo royal engagement at a black-tie private dinner at Clarence House.

An official statement explained that ‘the scar related to a childhood operation’, but said that details of the surgery were a private matter.

Carole Middleton featured alongside the Prince and Princess of Wales and their three children, in the touching three-minute family video revealing that Kate had finished her course of chemotherapy in September

Marlborough College, where textile designer William Morris, poets John Betjeman and Siegfried Sassoon, and Samantha Cameron, the wife of the former prime minister David, also studied

Carole and Kate share a joke while visiting the Spirit Of Christmas shopping festival at the Olympia exhibition centre in London in 2005

Kate and Carole enjoy a day out at the races at Royal Ascot in 2017

The Princess of Wales revealed in a video released in September that she had completed her course of chemotherapy after being diagnosed with cancer

Kate’s father Michael Middleton was also seen in the video, playing cards with the Prince and Princess of Wales and their children

Royal sources confirmed that it had been ‘a very serious operation’ but declined to comment further.

John Scurr, a consultant surgeon at the Lister Hospital in south-west London, said at the time that the scar was unlikely to have been the result of a tumour.

‘I really doubt it was any serious medical condition and I would say it is as a result of an arteriovenous malformation – a birthmark – being removed,’ he said.

‘It is remarkable, given the measurement, that no one has noticed before.’

Kate is not alone in having a prominent childhood scar on her head. Her husband William  bears a large zig-zag mark on his forehead as a result of being hit with a golf club when he was 13. 

Privately the pair are said to refer to their wounds as their ‘Harry Potter scars’, according to Nicholl.

According to Hello! magazine, he suffered the injury in 1991 while he was playing golf with friends at school in Wokingham.

The eight-year-old prince suffered a fractured skull and had an operation at Great Ormond Street children’s hospital in London. The scar becomes inflamed when he plays sport.

Prince William suffered a fractured skull in a golfing accident when he was a child and underwent surgery at Great Ormond Street children’s hospital. His mother, Diana, stayed with him overnight

Prince William has been left with a scar after a golfing accident when he was eight years old.  He calls it his ‘Harry Potter scar’, like the one on the forehead of the films’ star Daniel Radcliffe

Kate’s scar could be also seen while she was out enjoying a walk with Prince William. He, too, has a scar on the left-hand side of his head

William told the story of the injury during an interview in 2009, saying: ‘Yeah, we were on a putting green and the next thing you know there was a seven-iron and it came out of nowhere and hit me in the head.’

Over the years he has been married to Kate, William has come to confide in Carole and she is now a close friend of his.

One expert has previously remarked how she has taught her son-in-law ‘how a loving and supportive family works’. 

She has provided a ‘real sense of normality amid any chaos’ for the prince since he married Kate in 2011, royal biographer Angela Levin told The Sun in 2021. 

Carole, alongside her husband Michael, continues to support the future king and queen from behind the scenes.